Acid alkylation of isoparaffins



May 13, 1947.

POLY MERIZER FRACTIONATOR POLYMERIZER 7 HEATER A. RQ'GOLDSBY ACID ALKYLAT ION OF ISOPARAFFINS Filed June 25, 1938 FRACTIONATORS SEPARATOR 2 Sheets-Sheet l ISO-PARAFFINS ARTHUR R. GOLDSBY INVENTOR BY I ATTORNEY y 1 1947- A. R. GOLDSBY ACID ALKYLATION OF ISOPARAFFINS Filed June 25, 1938 2 Sheets-Sheet 2 now mmzwuum ATTORNEYS Patented May 13, 1947 ACID ALKYLATION F ISOPARAFFIN S Arthur R. Goldsby, Beacon, N. Y., assignor, by mesne assigmnents, to The Texas Company, New York, N. Y., a corporation of Delaware Application June 25, 1938, Serial No. 215,736

Claims.

This invention relates to the manufacture of motor fuels and has to do with the production of hydrocarbons of gasoline boiling range by the alkylation of paraffins with olefins. More particularly, the invention has to do with the alkylation of isoparafilns, such as isobutane, with normally gaseous olefins.

An important object of the invention is to alkylate an isoparafiin with a selected type of olefin.

Another object of the invention is to utilize a gaseous hydrocarbon mixture containing olefins and paraiiins whereby an isoparafiln may be alkylated with the desired olefin.

In accordance with the invention, an unsaturated hydrocarbon mixture containing olefins of two to five carbon atoms is separated into fractions containing olefins of the same number of carbon atoms and then an isoparafiin is alkylated with these olefin fractions.

The unsaturated hydrocarbons suitable for treatment may comprise normally gaseous hydrocarbons resulting from the cracking of hydrocarbon oils or gases, the destructive hydrogenation of heavy hydrocarbons, the dehydrogenation of normally liquid or normally gaseous hydrocarbons; or, normally gaseous hydrocarbons resulting from special conversion operations, such as the synthesis of hydrocarbon oils from water gas. The isoparaffins may be normally gaseous or normally liquid, for example, isoparafiins of not substantially higher boiling range than gasoline, for example isobutane or isopentane.

The separation of the olefins may be effected by the use of selective absorbents or selective polymerizing agents, for example, an acid, such as sulfuric acid or phosphoric acid. Methods which are specifically contemplated include the selective polymerization with a solid phosphoric acid catalyst of the type, and according to the method, described in the Ipatieif Patent No. 2,101,857, December 14, 1937; and the selective absorption with sulfuric acid according to the process disclosed in the Taveau Patent No. 1,810,192, June 16, 1931. The alkylation operation is preferably conducted in the presence of sulfuric acid catalyst. in accordance with the general method disclosed in the co-pending application of Korpi- Goldsby, Serial No. 148,978, filed June 18, 1937.

The invention will be more clearly understood from the following description read in connection with the accompanying drawings, which show diagrammatic sketches of apparatus suitable for carrying out the process of the invention.

Figure 1 shows an apparatus for practicing the invention when using as a step of the process the selective polymerization of the olefins by a catalyst comprising phosphoric acid to selectively polymerize the olefins. Figure 2 shows an apparatus for use in a modification of the invention wherein the olefins are selectively absorbed with sulfuric acid. The drawings are obviously diagrammatic and are subject to variations to accomplish the intended purpose of segregating the various olefins in the hydrocarbon mixture and then selectively alkylating an isoparafiin, such as isobutane, with these separated olefin fractions or polymers thereof.

Referring to Figure 1, the olefin charging stock which is preferably a hydrocarbon gaseous mixture comprising principally parafiins and monoolefins of three and four carbon atoms is introduced from a suitable source of supply, not shown, through the line 5 in which is located a valve 6 and pump 1. The hydrocarbons are passed through a coil 9 located in a heater l0 wherein they are heated under a suitable pressure to sufficient temperatures to selectively polymerize the isobutene when contacted with a solid phosphoric acid catalyst comprising a calcined mixture of phosphoric acid, preferably pyro-phosphoric acid, and kieselguhr. The heating coil is maintained at a temperature of about to 150 F., preferably about F. and a pressure of 50 to 100 pounds, preferably about 100 pounds. The products are passed through the transfer line l2 to catalyst chamber l3 in which is located the catalyst. While one polymerizing chamber is shown it is to be understood that any number, connected in series or parallel, may be used. In the polymerizer l3, the isobutene is selectively polymerized, or a cross polymerization of one mol of isobutene with one mol of normal butylene is obtained. In the case of such cross polymerization, somewhat more drastic conditions of temperature and pressure than given above are desirable. The reaction products are passed from the lower portion of the catalyst chamber I3 through the valve controlled line H to a fractionator l5 wherein the normally liquid hydrocarbons or polymers are condensed and withdrawn from the lower portion thereof through the line I! to be discharged from the system through the branch line H3 or delivered through the line 20 to a subsequent alkylation operation, more fully described hereinafter.

The normally gaseous hydrocarbons, after the separation of the polymers, are withdrawn frOm the upper portion of the fractionator l5 through the vapor line 22 and forced by the pump 23 to a coil 24 located in a heater 25. In the coil 24 to a second polymerizer or catalyst chamber 30' wherein they are contacted under approximately the conditions prevailing in coil 24 with solid phosphoric acid catalyst. The reaction products are transferred from the catalyst chamber i) through the valve controlled line' 3| to a frac tionator 32 wherein the polymers are separated and withdrawn from the lower portion thereof through the line 33. The polymers so withdrawn may be discharged from the system through the branch line 34 or passed through the line 35for' subsequent alkylation.

The normally gaseous hydrocarbons fractionated'. out in the fractionator 32 should be substantially free from C4 olefins, and may contain C3 together with lighter olefins, if any. These gase's are passed from the top of fractionator 32 through, the line 3! to coil 58 located in the heater 4-0. Pressure may be reduced on these gases by means of the valve 4| and the temperature raised in the heating coil 33 to a point such thatathe: propylene in the gases will be polymerizedinpthe vapor phase when contacted with solid phosphoric acid catalyst. Temperatures should be above 250 and maybe ashigh as 500 F., preferably about 40o to 500 F. Pressure may range fromuabout 100 to 300 pounds per square inch. The products are transferred from the heater through the line 342 to the polymerization chamber 43 which contains the catalyst. In the polymerization chamber the propylene is polymerized to form a large proportion of material fallingwithinthe gasoline boiling point range, for example hexenes. The polymerization products are conducted from the polymerization chamber through the valve controlled hne 45 to a-fractionator 43 wherein the polymers are fractionatedout and withdrawn from the lower portion thereofthrough the line M.- Any portion of these polymers; may be discharged from the sys-' tem'throughthe valve controlled line 45!. It is intended. however, that the polymers be conducted through the valve controlled line 50 to be used-as charge. to an alkylation operation. The remaining normally gaseous hydrocarbons are discharged fromthe top of the fractionator 45 through the valve controlled line 52.

When operating on C3 and C4 hydrocarbon fractions, the gases discharged from the top of the-fraction'atorwill consist largely of propane and butanes. It may be desirable in some cases to condense a large portion of the butanes along with the final polymer withdrawn from the fractionator 46'. These butanes may be utilized to impart volatility to the finished gasoline or the isobutane therein may be utilized as a portion of the isopara'ffins which are alkylated in the subsequent alkylation operation. If the charging stocks contains'ubstantial quantities of hydrocarbons of lower boiling point than C3 hydrocarbons, for example C2 hydrocarbons, including ethylene, it maybe desirable to employ a fourth stage of polymerization in which the ethylene would be polymerized to produce an additional quantity of polymers useful as a source of olefins in the alkylation operation. By usin suitable time, temperature and pressure conditions, for example temperatures of 550 to 700 F., pressures above 300 pounds and a contact time of at least 300 seconds, the ethylene may be polymerized to polymers which may be used for alkylation. Such a fourth stage of polymerization is not shown on the drawing.

The polymers'withdrawn through the lines 20, 35 and 55. referred to heretofore, are discharged into suitable receivers or tanks 54, 55 and 55 respectively. These tanks are provided with valve controlled draw-off lines 58, 59 and 60 for charging the contents thereof to an alkylation system. Forthe purpose of utilizing these stocks as alkylation charges, they may be passed into the line GI and forced by the pump 52 to an alkylation vessel it. In this vessel the olefins are contacted with the necessary amount of isoparafiin which may be introduced through the line 65 by the pump 55, and with a suitable quantity of an acid catalyst, introduced through the line 6'! by pump 68. The isoparafiln, such as isobutane, is introduced in such amount that'the ratio of isobutane to olefin in the reaction mixture is in excess of 1:1 and preferably between about 3:1 and 5:1. The catalyst is preferably sulfuric acid of alkylationstrength and preferably about 94- to 98%. The amount of acid may be 500-800% by weight based on the olefin and the major part thereof may be recycled.

The mixture is transferred from the vessel 10 through the line 12 to a second alkylation vessel 14. In these tanks suificient time is provided to effect substantial alkylation of the paraflins by the olefins, for example about 45 to 90 minutes and preferably about 50 to 60 minutes. The alkylation tanks are provided with means for producing as intimate contact as possible between the acid and the hydrocarbons by the use of stirrcrs l5 and 76 or other suitable mechanism, While two alkylation-tanks are shown, it is to be understood that any number may be used, and the operation may be modified to use the counterfiow principle for contacting the acid and the hydrocarbons, if desired. The reaction products are conducted from the last alkylation tank through the line 11 to a separator l8wherein separation is allowed to take place between the acid and the hydrocarbons. If desired, any portion or all of the reaction products instead of being charged into the separator may be recirculated through the by-pass line 19 and the line containing pump 8| to the alkylation operation. The acid separatingout in the separator 18 may be:withdrawn from the systemthrough the valve-controlled line 8-2; It is preferable,- howeveatolrecycle a portion or all of thisacid to the alk'lation operation through the lines 83 and- 80.

The hydrocarbons settling out in the. separator 78 are passed throughthe line 85m a mixer 85 wherein they are intimately contacted witha neutralizing agent,: such as anaqueousalkali, for

example, dilute soda ash, introduced through the" from the top of the fractionator through the valve controlled line 96. The liquid hydrocarbon fraction is withdrawn from the lower portion oi the fractionator through the line 91 and discharged into a secondary fractionator 98 wherein the liquids are fractionally distilled to separate, as a. liquid residue, the high boiling liquids or bottoms, of higher boiling range than gasoline, which are withdrawn from the lower portion of the fractionator through the valve controlled line I00. The vapors containing the gasoline are conducted overhead through the vapor line IIII to a condenser I02 wherein the vapors are condensed and the condensate passed through the run-down line I03 to an accumulator I04.

While only one alkylation unit is shown for the treatment of the various olefinic polymers from the separate stages of polymerization, it is contemplated that any number of alkylation units may be used, for example one for each polymer fraction. Multiple injection of the olefins or polymers into two or more of the alkylation tanks may be used to improve the yield and quality of the product. It is to be understood that various mixtures of the separate polymers may be utilized, if desired, as a charging stock to the alkylation operation. Moreover, if desired, the separate polymers may be blended as desired and the blend utilized as a charging stock to the alkylation operation.

The alkylation operation is preferably carried out in the liquid phase which may be obtained by applying suflicient pressure, for example about 25 to 150 pounds, to maintain the products in the liquid phase. The temperatures ordinarily employed range from about zero to 125 F., preferably about 60 to 90 F. If the various polymers are alkylated separately, the temperature and pressure conditions may be regulated to obtain optimum results, from the standpoint of yield and antiknock value.

In the foregoing description of the process of the invention, normally gaseous olefins are selectively polymerized in the vapor phase to obtain olefinic polymers which are in general normally liquid products. These normally liquid products are used in the alkylation of isoparaffins, such as isobutane, to obtain branch chain hydrocarbons within the gasoline boiling range and having a high antiknock value.

In the modification of the invention to be described hereinafter, normally gaseous olei'in hydrocarbons are separated by absorption in sulfuric acid of the proper strength to selectively absorb the various olefins in the mixture; the olefins thus separated may be subjected to alkylation without polymerization thereof, although it is contemplated that the absorbed olefins may be polymerized, particularly the C4 olefins, such as isobutylene. It is intended, however, to selectively absorb the olefins in the sulfuric acid and then use the acid mixture in the alkylation operation. In the case of olefins of lower molecular weight, strong acid is required in the absorption operation and the resulting acid mixture may be used with little difi'iculty in the subsequent alkylation operation since a relatively strong acid is also required in the alkylation step. In the case of higher molecular weight olefins, weaker acids are generally required and it may be desirable in these cases to polymerize the olefins and use the polymers, but the acid mixture may be used without the intermediate polymerization by building up the acid mixture to a strength suitable for alkylation.

Referring to Figure 2, the hydrocarbon char ing stock may comprise a hydrocarbon mixture containing C4 olefins, C3 and C4 olefins or C2, C3 and C4 olefins, as well as various amounts of parafiins of the same molecular weight. This charging stock is introduced through the line I05 and forced by the pump I through the line I98 to a series of absorbers IID, III and H2, wherein the hydrocarbons in gaseous phase are contacted with acid introduced through the line H4 by the pump H5. The acid may be sulfuric acid of about 60 to 75% concentration and preferably about 65 to 66%. At a temperature of about 30 C. or below, the acid absorbs preferentially the isobutylene. The acid and hydrocarbons pass countercurrently through the absorber I III, the unabsorbed hydrocarbons passing out of the top of the absorber through the line H6 and into the lower portion of the absorber III. The acid and absorbed hyrocarbons are conducted from the lower portion of the absorber III! through the line I I! in which is located a pump II8 to the upper portion of the absorber I I I. The acid and hydrocarbons recontacted in the absorber III, the hydrocarbons passing from the top of the absorber I I I through the line I20 to the lower portion of the absorber IIZ, while the acid is pumped from the lower portion of the absorber III by the pump I2I through the line I22 to the upper portion of the absorber H2. While three absorbers are shown, it is contemplated that any number may be used to obtain the desired results. The unabsorbed hydrocarbons are released from the top of absorber II2 through the valve controlled line I24. Under the conditions specified, substantially all the isobutylene should be preferentially absorbed by the acid.

The acid mixture containing absorbed isobutlyene is withdrawn from the bottom of absorber II2 through the line I25 and is forced by the pump I26 to an alkylation system referred to hereinafter. Any portion of the acid mixture may be withdrawn through the line I25 and may be recycled to the absorbers through the branch line I 21 by the pump I28. The acid mixture from line I25 is introduced into an alkylation tank I35 wherein it is contacted with strong acid of suitable strength, for example 98 to in sufficient amount to raise the acidity of the mixture to about 94. to 96%. Such strong acid may be introduced through the line ISI in which is located a pump I52. The acid mixture in the vessel I30 is also contacted with an isoparaifin, such as isobutane, introduced through the line I34 and pump I35. Sufiicient isobutene is added to bring the ratio of isobutane to olefins in the mixture to at least 1:1 and preferably about 3:1. The products are passed from the vessel I39 through the line I36 to a second alkylation tank I38. The reaction taking place in the alkylation tanks is essentially the alkylation of isobutane with isobutylene to form normally liquid hydrocarbons. While the nature of the reactions is not fully understood, it is believed that a reaction takes place between the isobutane and the acid hydrocarbon compounds, which may comprise alkyl sulfates, to produce branch chain hydrocarbons comprising a substantial amount of isooctane. The conditions maintained in the alkylation tanks are essentially the same as those described in connection with Figure 1.

The alkylation products pass from the last tank I38 through the line I44 to a separator I45. Any portion of this mixture from line I44 may be recycled through the alkylationtanks by theline I41 and pump I48. In the separator I45 the acid.

settles out from the hydrocarbons in the lower portionthereof and may be withdrawn through the line. I50 or recycled to the alkylation tanks through the lines I and I41. The hydrocarbons in the upper layer pass from the separator I45 through the line I52 to a mixer I53. An alkaline neutralizing reagent, such as. soda ash solution, is introduced into the mixer I53'through the line I55 containing pump I56 tolneutralizeany acid in the oil. The mixture passes from the mixer through the line I51 to a separator I58. The alkaline solution separates from the oil in separator I58 and may be withdrawn from the system through the line I 59 or recycled to the mixer I53 by the pump I60 through the line ISI. The hydrocarbon layer separating in the separator I58. is. withdrawn through the line I03 to a fractionator I54. In this fractionator the oil is distilled to separate the hydrocarbons of gasoline boiling point and lower as vapors, while the bottoms of higher boiling point than gasoline are withdrawn as bottoms from the lower portion of the fractionator, through the valve controlled line I55. The gasoline vapors pass overhead through the vapor line I61 to condenser coil I68 where the vapors are condensed and the resultant distillate passes through a rundown line I to a receiver I1I.

The acid mixture withdrawn from the lower portion of absorber II2 through the line I25, according to one modification, may be passed through the branch line I14 to polymerization vessel I15. In this vessel the mixture is raised to su-flicient temperature, for example about 180 to 200 F. by suitable heating, for example in steam coil I16. At this temperature the absorbed olefins, for example isobutylene, polymerizes chiefly to the dimer or di-isobutylene which separates as an oil layer and is withdrawn from the vessel I through the line I11 to a fractionator I18. The acid layer collecting in the vessel I15 may be withdrawn through the line I13. A portion or all of this acid may be returned through the branch line I19 and line I21 to the absorbers. In the fractionator the polymers are separated from lower boiling hydrocarbons, including unreacted isobutylene, as bottoms which are withdrawn from the lower portion of the fractionator through the line I80: which communicates with the line I leading to the mixer I30. The polymer may be subsequently treated as described heretofore with acid and isoparaifin to obtain high antiknock gasoline by alkylation. The overhead products from fractionator I10 are passed through the vapor line -I8I and condenser I82 to a receiver I83. The products from the receiver I83 may be conducted through the line I8 to be subsequently treated as described hereinafter.

The hydrocarbons withdrawn through the line I24 from the top of the absorber I I2, with or without those from receiver I83 are forced through the line I 85 by the pump I186 to the first of a series of absorbers I 88. These hydrocarbons should be substantially free from isobutylene and may comprise isomeric normal butenes, propylene and ethylene. In the absorbersthe hydrocarbons are contacted with an acid introduced through the line I89 by the pump I90. The acid should be of sufiicient strength, for example about 80% to 90% concentration and preferably about 85% to absorb the isomeric butenes. The products are conducted through a plurality of absorbers I80, I92 and I93 connected in series by the acid lines. I95 and I95 and the hydrocarbon lines I91 and I98. The absorption of the isomeric butenes is effected in these absorbers at a temperature preferably not over 30 C. The acid mixture passes out of the last absorber I93 through the line. I 99 to a separator 200. Any portion of the acid mixture may be recycled through the absorbers by the line 2.0I in which is located pump 202. In the separator 200 a separation is made between the acid and hydrocarbon vapors, the latter passing out of the separator to the vapor line 204. The acid mixture containing the absorbed olefins is withdrawn from the separator through the line 205 and forced by the pump 205 through the line 201 to an alkylation tank 208. Any portion of this acid mixture may be recycled to the absorbers through the branch line 203 and the recycle line 20-I.

In the tank 208 the acid mixture is preferably fortified by a stronger acid in sufficient quantity to build the acidity up to about 95% or over. For this purpose a stronger acid, such as sulfuric acid, of 98% strength or higher, is introduced through line .299 by the pump 2I0. There is also introduced into the tank 208 isobutane through the line 2 by pump 2I2 in suflicient amount to produce a ratio of isobutane to olefins of about 3:1. The resultant mixture is passed from the mixer 208 through the line 2 I4 to a second alkylation tank 2I5 The tanks may be any suitable number, but are shown as the two tanks 2I5 and 208 connected in series by the line 2I4. The conditions maintained in these alkylation tanks are substantially the same as those described heretofore in connection with the tanks I30 and I38. It is intended to effect alkylation of the isobutane by the olefins to produce high antiknock gasoline hydrocarbons.

The reaction mixture is withdrawn from the tank 2I5 through the line 222 to a separator 223. A recycle line 224 containing pump 225 may be used for recycling any portion of the mixture in line 222 through the alkylation tanks. In the separator 223 the hydrocarbon alkylation products separate from the acid as a hydrocarbon layer which may be withdrawn through the line 221-. The acid layer may be withdrawn from the bottom of the separator 223 through the line 228 and a portion or all of this acid maybe recycled to the system through the branch line 229 and line 224. The hydrocarbon from the separator 223 passthrough the line 221 to a mixer 230 wherein the hydrocarbons are contacted with a neutralizing agent, such as an aqueous alkali, for xample dilute caustic alkali solution, introduced through the line 23I by the pump 232. The mixture is transferred from mixer :23!) through the line 234 to a separator .235 wherein the neutralizing agent separates out and may be withdrawn through the line 236 or recycled to the mixer 230 through the line 231 by the pump 238. The neutralized hydrocarbons are conducted from the separator 235 through the line 240 to a fractionator 24!. In the fractionator the hydrocarbons are subjected to fractional distillation to separate the higher boiling hydrocarbons as bottoms which are withdrawn through the line 242 while the lower boiling hydrocarbons comprising gasoline are removed overhead as vapors through the vapor line 243 and thence through the condenser coil 24.4 and run-down line 245 to an accumulator 245.

The hydrocarbon withdrawn from the separator 200 should be substantially free from C4 olefins and may comprise propylene and ethylene, along with various saturated hydrocarbons. These unreacted hydrocarbons are forced by the pump 250 through the line 25I to an absorber 252 wherein they are contacted with an acid, of sufficient strength to absorb the propylene, introduced through the line 253 by the pump 254. The acid should be at least 90% concentration, preferably about 94% or stronger. The mixture is conducted through a series of absorbers 252, 255 and 256, connected in series by acid lines 251 and 258, and the hydrocarbon lines 259 and 269. The temperature maintained in the absorbers is suitable for the absorption of propylene, preferably under 30 The products are conducted from the absorber 256 through the line 26! to a separator 262. Any portion of this acid mixture may be recycled by the pump 263 to the line 264. In the separator 262 the unabsorbed hydrocarbons separate and may be withdrawn through the valve controlled line 265. The acid and absorbed olefins are withdrawn from the lower portion of the separator through the line 261 and forced by the pump 268 through the line 269, to an alkylation tank 210. A branch line 212 is provided whereby any portion of the acid mixture from line 261 may be recycled to the absorbers, through the connect ing line 264.

In the tank 219 the acid containing absorbed olefins is contacted with isobutane introduced through the line 21! by pump 213. The amount of isobutane. introduced should be about three times that of the olefins contained in the acid mixture. The acid may be of sufficient strength to cif ect the intended alkylation of isobutahe by the olefins. In case the acid, however, is of substantially lower concentration than 94%, it is desirable to introduce suflicient stronger acid through the line 214 by pump 215 in sufficient amount to bring the concentration of the acid mixture to 94% or above and preferably about '95 to 96%. This acid mixtureis thenconducted through the alkylation tanks 210 and 216 wherein the desired alkylation reaction takes place under :substantiali'y the same conditions as described heretofore. The alkylation products are conducted to the separator 218 although any portion thereof may be recycled through the line 219 by pump 2%. In the separator 218, the acid is separated and withdrawn through the line 28l or recycled to the system through the lines 282 and 219. The hydrocarbons are conducted through the line 283 to a mixer 285 wherein they are contacted with a neutralizing agent, such as aqueous caustic soda, introduced through the line 286. The mixture is then transferred through the line 281 to a separator 288 wherein the neutralizing agent is separated and withdrawn through the line 289 or recycled through the line 290. The neutralized hydrocarbons are passed through the line 29! to a fractionator 292 wherein hydrocarbons are distilled to separate the gasoline fraction which is removed overhead through the vapor line 293 and condenser 29A to receiver 295, while the polymers higher boiling than gasoline are withdrawn from the bottom of the fractionator through the line 296.

The unreacted gases removed through the line 265 from separator 262 should be substantiallyfree from olefins with the exception of ethylene. These hydrocarbons may be further treated to remove the ethylene by contacting the gases with concentrated acid, such as 94% or higher, at temperatures of about 89 to 90 C. and under high pressures, for example in excess of 450 pounds,

10 ethylene is absorbed. The acid containing the absorbed ethylene may be utilized for alkylating isoparafiins, under suitable conditions for alkylation. Such further treatment of the ethylene containing gases is not shown in the drawings.

As an example of the operation of the invention, unsaturated hydrocarbon gases from a cracking still, comprising essentially C3 and C4 hydrocarbons, were subjected to polymerization by contacting them with a phosphoric acid catalyst comprising a calcined mixture of pyro-phosphoric acid and kieselguhr. The temperature was about 100 F, and the pressure about 100 pounds. A polymer was separated comprising largely diisobutylene. The unreacted gases were subjected to further polymerization in the presence of a similar catalyst, at temperatures of about 200 F. and 250 pounds pressure, whereby the isomeric butenes were polymerized and separated as a polymer. The unreacted gases were further subjected to polymerization in the presence of a similar catalyst at temperatures of about 500 F. and a pressure of about 250 pounds to polymerize the propylene which was separated as a polymer. The three polymers were separately subjected to an alkylation reaction in the presence of isobutane and sulfuric acid of about 96% concentration. A gasoline fraction was separated from each of the polymerization .products. The gasoline from the treatment of the di-isobutylene had an octane rating of about 92 and contained a substantial amount of iso-octane. The gasoline from the alkylation of the isomeric butene polyiner hadan octane rating of around 90 and also had a substantial iso-octane content. The gasoline obtained from the alkylation products utilizing the propylene polymer had an octane rating of about 85 and contained a substantial amount of iso-heptane.

As another example of the operation of the invention, a C4 unsaturated hydrocarbon fraction derived from a cracking still was contacted with sulfuric acid of about strength at a temperature of 30 0., whereby the isobutylene was absorbed. The acid mixture was fortified with strong acid of sufficient strength to bring the acidity up to about 95%. The resulting product was subjected to an alkylation operation in the presence of isobutane, whereby an alkylation product was produced in which gasoline was separated having an octane value of about 92 containing a large amount of iso-octane. The unreacted gases containing the isomeric normal butenes were contacted with sulfuric acid of about strength at a temperature of about 30 C. to absorb the butenes. The mixture of acid and absorbed butenes was fortified with strong acid to bring the acidity up to about 95% and the resultant mixture subjected to alkylation in the presence of isobutane. A gasoline fraction was separated from the alkylation products having an ,in the-absorption orthe alkylation stages of the gisomfiric butylene or the isobutylene,

In case undesirablepolymersare formed in the absorption stages of the process, it is contemplated that any portion or all of these polymers may be separated from the acid mixture prior to alkylation thereof. This separation step is not shown in the drawings.

The absorption of the olefins in the acid may take .place either in the liquid or vapor phase by adjusting the temperature and pressure conditions. The liquid phase, of course, will increase the surface of contact between the hydrocarbons and absorbent.

An advantage of the present invention is the alkylation of relatively pure olefins which often produce increased yields over thosepossible when treating the mixtures of olefins, Furthermore, it is possible to produce from the various olefins, difierent types of alkylation products, which are often desirable as special fuels or as blending agents to improve the antik'nock and volatility characteristics of certain fuels.

The feature in the catalytic alkylation of an olefinie feed stock comprising a more reactive olefin and a less reactive olefin, involving the separation of the more reactive olefin from the feed stock, alkylating the more reactive olefin with a less concentrated alkylation catalyst, alkylating the less reactive olefin with a more concentrated alkylation catalyst, and supplying catalyst withdrawn from the less reactive olefin alkylation zone'to the more reactive olefin alkylation zone to serve as the alkylation catalyst in the latter, is disclosed and claimed'in applicants divisional application, Serial No. 519,759, filed January 26, 1944. Likewise, the inventions involving separation of an olefin or various olefins by a catalytic polymerization step or steps, in combination with catalytic alkylation, are also disclosed and claimed in said divisional application, and in applicant's copending application, "Serial No. 482,269,fi1ed April 8, '1943.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such-limitations should-be imposed as are indicated in the .ap-

pended claims.

I claim: 1. A process for the alkylation of isoparaihns with olefins, which comprises reacting the olefin with sulfuric acid'to form an alkyl sulfuric acid compound, separatingsaid acid compound and then reacting said compound in the presence of strong sulfuric acid with an isoparafiin to form a branch chain saturated hydrocarbon compound.

2. A process for the treatment of hydrocarbons containing propylene, which 'comprises absorbing the propylene in strong sulfuric acid of over 90% concentration, thentreating the acid solution at temperatures not in excess of about 125F. with additional strong acid and isdbutane whereby the isobutane is alkylate'd by the absorbed propylene to form saturated normallyliq uid hydrocarbons within the gasoline iboiling range.

'3. A process for-the alkylationof .isoparaifins with olefinscomprising absorbing normailygaseo'us olefins in concentrated'sulfuric "acidand'reacting an isoparafiinwiththe absorption mixture of 'olefin's and concentrated sulfuric acid in the presence of concentratedsuifuricacid and under alkylati'on conditions of operation to effect alkylati'on of the isoparafiin withlsaid olefins.

'4. A process of alkylatinganisoparaifinwvhich 12 comprisesforming an alkyl ester of sulfuric acid, thereafter contacting and reacting said .preformed alkyl sulfate with an isoparafiin in the presence of concentrated sulfuric acid and under alkylatio'n conditions of operation to effect alkylation of the isoparafiin with said ester.

5. in a process involving alkylation of a satu-- rated hydrocarbon with an olefin derivedfrom a petroleum base "feed stock, the improvement which comprises absorbing the olefin from the feedstock with sulfuric acid to produce an acid solution of the esterifie'd olefin, separating the solution from the residual feed stock, and reacting the separated solution with an isoparafin in'the presence of concentrated sulfuric acid under'alkylation conditions to form an alkylate.

6. A process for the alkylation of an isoparaflin with an olefin which comprises absorbing the olefin in sulfuric acidin one step, then alkylating the absorbed olefin product in a second step with an Isoparaflin in the presence of concentrated sulphuric acid under alkylating conditions, andr'ecyclin'g acid from the alkylation step to the absorption step.

'7. A process for the alkylation of an isoparafiin with an olefin which comprises reacting the olefin with an acid to form a corresponding alkyl ester, and then alkylating the said alkyl ester with an iso'parafiin in the presence of concentrated sulfuric acid under alkylating conditions.

8. A process for the alkylation of an isoparaflin with an olefin, which comprises reacting the olefin with sulfuric acid to form a solution of a correspondin alkyl sulfate in the sulfuric acid and wherein the strength of the resulting acid is less than about concentration, fortifying the 'acid'solution to bring the acid concentration up to above 90%, and'then alkylating the fortified solution with an isoparaffin under alkylating conditions to produce normally liquid hydrocarbons within the gasoline boiling range.

9. A process for the alkylation of a low boiling isoparafiin with a low boiling olefin utilizing an olefinic hydrocarbon 'fraction containing paraf- 'fini'c hydrocarbons in addition .to the olefin,

which comprises passing the hydrocarbon fraction countercurrent to a mineral acid inan absorption zone to thereby'absorb the olefin from the hydrocarbon fraction, removing unabsorbed hydrocarbons adjacent one end of the absorption zone and acid containing absorbed olefin adjacent the other end of the absorption zone, and alkylating the absorbed olefin'with a low boiling isoparafiin in the presence of concentrated sulfuric acid under alkylating conditions.

10. -A process of alkylating 'an isoparaflin having less than 6 carbon atoms per molecule to make high anti-knock gasoline boiling hydrocarbons, 'which comprises reacting less concentrated sulfuric acid with an olefin which forms therewith 'an alkyl ester of said sulfuric acid, then alkylating an isoparaflln 'havingless than '6 carbon atoms per molecule with the resulting alkyl ester in a'second zone in the presence of more concentrated sulfuric acid of alkylation strength effective tocause alkylation of the isoparafiin with the. said alkyl ester.

11.'In aprocess involving alkyklation o1 isobutane and a butylene, the improvement which comprises treating a petroleum base feed stock containing a butylene and isobutane with sulfuric acid to producea sulfuric acid solution of esterified butylene, separating the solution from the residual feedstock, reacting the'separated solution with 'a large excess of isobutane in the pres- 13 ence of concentrated sulfuric acid under alkylating conditions to form alkylate, separating the resulting spent acid from the said alkylation step, and returning the separated spent acid for admixture with additional feed stock in the absorption step.

12. A process for the alkylation of an isoparafjn with an olefin which comprises reacting the olefin with an acid to form a corresponding alkyl ester, and then alkylating an isoparafiin with said alkyl ester in the presence of a corresponding acid alkylation catalyst under alkylating conditions.

13. A process for the manufacture of substantially saturated gasoline hydrocarbons of high anti-knock value which comprises feeding an isoparaffin and an alkyl sulfate into a reaction zone, with the isoparafiin maintained in substantial molar excess of the alkyl sulfate, and reacting the isoparaifin with said alkyl sulfate in said zone in the presence of Strong sulfuric acid under alkylating conditions to produce substantially saturated gasoline hydrocarbons.

14. In a process for the manufacture of gasoline hydrocarbons of high anti-knock value from an isoparafiin and an olefinic refinery fraction, the method which comprises absorbing the olefin from the refinery fraction with an acid to produce an acid solution of the esterified olefin, separating the solution from the residual unabsorbed refinery fraction, and reacting an isoparafiin with the separated esterified olefin in the presene of a corresponding acid alkylation catalyst under alkylating conditions.

15. The method in the alkylation of a low boiling isoparaffin with a low boiling olefin for the production of motor fuel hydrocarbons utilizing an olefinic feed stock containing a more reactive olefin and a less reactive olefin, which comprises treating the olefinic feed stock under conditions 14 to selectively remove the more reactive olefin, then treating the remaining feed stock with sulfuric acid of absorption strength for the less reactive olefin under conditions to react with the less reactive olefin to form the corresponding alkyl ester, alkylating the said alkyl ester with a low boiling isoparaffin in the presence of sulfuric acid of alkylation strength under alkylating conditions to produce substantially saturated hydrocarbons within the gasoline boiling range, and separating a substantially saturated hydrocarbon fraction within the gasoline boiling range from said alkylation products.

ARTHUR R. GOLDSBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,001,906 Ipatieif May 21, 1935 2,001,910 Ipatieff May 21, 1935 1,810,192 Taveau June 16, 1931 2,007,159 Engs et a1 July 9, 1935 2,007,160 Engs et a1 July 9, 1935 2,014,724 Eastman Sept. 17, 1935 2,101,857 Ipatieif et a1 Dec. 14, 1937 2,300,817 Sweeney et al Nov. 3, 1942 2,211,747 Goldsby et al Aug. 13, 1940 2,170,306 Ipatiefi et a1. Aug. 22, 1939 2,169,809 Morrell Aug. 15, 1939 FOREIGN PATENTS Number Country Date 479,345 Great Britain Jan. 31, 1938 479,827 Great Britain Feb. 11, 1938 824,914 France Nov. 18, 1937 824,329 France Nov. 10, 1937 

